300 TROPICAL NATURE III 
thologists, it will. be better to consider the series of fifty 
families of Passeres as one compact group, and endeavour to 
point out what external peculiarities are most distinctive of 
those which inhabit tropical countries. 
Owing to the prevalence of forests and the abundance of 
flowers, fruits, and insects, tropical and especially equatorial 
birds have become largely adapted to these kinds of food ; 
while the seed-eaters, which abound in temperate lands where 
grasses cover much of the surface, are proportionately scarce. 
Many of the peculiarly tropical families are therefore either 
true insect-eaters or true fruit-eaters, whereas in the tem- 
perate zones a mixed diet is more general. 
One of the features of tropical birds that will first strike 
the observer is the prevalence of crests and of ornamental 
plumage in various parts of the body, and especially of ex- 
tremely long or curiously shaped feathers in the tails, tail- 
coverts, or wings of a variety of species. As examples we 
may refer to the red paradise-bird, whose middle tail-feathers 
are like long ribands of whalebone ; to the wire-like tail 
feathers of the king bird-of-paradise of New Guinea, and of 
the wire-tailed manakin of the Amazons; and to the long 
waving tail plumes of the whydah finch of West Africa and 
paradise flycatcher of India,; to the varied and elegant crests 
of the cock-of-the-rock, the king-tyrant, the wmbrella-bird, 
and the six-plumed bird-of-paradise ; and to the wonderful 
side plumes of most of the true paradise-birds. In other 
orders of birds we have such remarkable examples as the 
racquet-tailed kingfishers of the Moluccas, and the racquet- 
tailed parrots of Celebes; the enormously developed tail- 
coverts of the peacock and the Mexican trogon; and the 
excessive wing-plumes of the argus-pheasant of Malacca and 
the long-shafted goatsucker of West Africa. 
Still more remarkable are the varied styles of. coloration 
in the birds of tropical forests, which rarely or never appear 
in those of temperate lands. We have intensely lustrous 
metallic plumage in the jacamars, trogons, humming-birds, 
sun-birds, and paradise-birds ; as well as in some starlings, 
pittas or ground thrushes, and drongo-shrikes. Pure green 
tints occur in parrots, pigeons, green bulbuls, greenlets, and 
in some tanagers, finches, chatterers, and pittas. These 
